createCanvas(400, 400);

  background(230, 230, 250);

​

  // center and size method

  rectCenter(200, 200, 100, 50); // centered rectangle

​

  // two corners method

  rectCorners(50, 50, 150, 150); // rectangle from top-left to bottom-right

}

​

function rectCenter(centerX, centerY, width, height) {

  rect(centerX - width / 2, centerY - height / 2, width, height);

}

​

function rectCorners(topLeftX, topLeftY, bottomRightX, bottomRightY) {

  let w = bottomRightX - topLeftX;

  let h = bottomRightY - topLeftY;

  rect(topLeftX, topLeftY, w, h);

}

​